This invention relates to a novel cathode-ray tube comprising a glass viewing window having, on its viewing surface, a glare-reducing image-transmitting silicate coating that is also antistatic; that is, it does not accumulate electronic charge on its surface.
Glare-reducing silicate coatings for the glass viewing windows of cathode-ray tubes have been disclosed previously. See, for example, U.S. Pat. Nos. 3,114,668 to G. A. Guiles, 3,326,715 to R. G. Twells, 3,635,751 to G. E. Long, III et al. and 3,898,509 to M. G. Brown, Jr. et al. Such coatings do not depend on destructive interference of the ambient light. Instead, the surfaces of these coatings have controlled roughnesses so that the ambient light is scattered in such manner that the brightness and resolution of reflections are reduced. The coatings may contain small amounts of fine carbon particles to reduce in a controlled manner the brightness of a transmitted light image.
When prior cathode-ray tubes with the above-mentioned coatings are operated, they accumulate static charge on the viewing surfaces of the coatings. Static charge on the viewing surface of a cathode-ray tube is objectionable from many standpoints. Static charge attracts dust to the viewing surface. Also, it can produce a mild electric shock when it is touched. Mild electric shock may occur where the tube is used for entertainment or for the display of data.